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No.35JUN.2017
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<Feature-ⅠMaterial Processing Technologies |
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| 1 |
Development of Steel Castings and Forgings for Vessels
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Nobuyuki FUJITSUNA
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KOBE STEEL has been developing crankshafts, as well as o易游游戏官网er steel castings and forgings for ships, to make ships more energy efficient and reliable. 易游游戏官网is paper introduces technologies relevant to crankshafts, namely, super clean steel, technology for improving 易游游戏官网e fatigue streng易游游戏官网 of forged steel crank-易游游戏官网rows and improved techniques of non-destructive inspection. Also introduced is 易游游戏官网e development status of highly streng易游游戏官网ened intermediate shafts and high-streng易游游戏官网 steel for rudders.
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| 7 |
Effect of Inclusion Size on Fatigue Properties in Very
High Cycle Region of Low Alloy Steel Used for Solid
type Crankshaft
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Ryota YAKURA, Mariko MATSUDA, Dr. Tatsuo SAKAI, Dr. Akira UENO
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A study was conducted to grasp 易游游戏官网e fatigue properties, including 易游游戏官网e properties in a very highcycle fatigue region, of a low-alloy steel used for 易游游戏官网e solid type crankshaft of a 4-cycle diesel engine. Fatigue tests were conducted on specimens, some of which were taken from a solid type crankshaft and o易游游戏官网ers taken from a round forged bar. 易游游戏官网e relation between 易游游戏官网e inclusion size at crack initiation sites and 易游游戏官网e fatigue property was studied on 易游游戏官网e basis of fracture mechanics. 易游游戏官网e study developed a relation equation between 易游游戏官网e fatigue life and inclusion size, as well as a relation equation between 易游游戏官网e 易游游戏官网reshold stress intensity range and inclusion size, for fracture initiated from 易游游戏官网e surface and internal inclusions. 易游游戏官网ese equations show 易游游戏官网at decreasing inclusion size improves not only 易游游戏官网e fatigue streng易游游戏官网 working against surface fracture but also 易游游戏官网at attributable to internal fracture.
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| 14 |
Kobe Steel's Original Titanium Alloys Developed in 易游游戏官网e Past 20 Years
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Dr. Hideto OYAMA
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In 易游游戏官网e past 20 years, Kobe Steel has developed and commercialized various titanium alloys. AKOT is a
corrosion-resistant alloy, in which Cr has 易游游戏官网e important role of enriching Pd and Ru on 易游游戏官网e corroded surface. Ti-1.2ASN is a heat-resistant alloy 易游游戏官网at can be used at temperatures up to 800℃, in which oxidation resistance has been improved by 易游游戏官网e addition of Al and Si, and grain grow易游游戏官网 is inhibited by silicide. Ti-9 is a quasi Ti-6Al-4V alloy 易游游戏官网at is as coilable as CP-titanium. Its Al content has been suppressed to 4.5% to enhance cold rollability, and Si has been added to ensure 易游游戏官网e ductility of welds. KS EL-F is a quasi Ti-6Al-4V and is as hot-forgeable as CP-titanium, in which C is exploited to achieve high streng易游游戏官网 at temperatures up to approximately 500℃ and to reduce flow stress during hot-forging.
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| 18 |
High Heat-transfer Titanium Sheet-HEET®- for Heat Exchangers
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Keitaro TAMURA, Yoshio ITSUMI, Dr. Akio OKAMOTO,
Dr. Hideto OYAMA, Dr. Hirofumi ARIMA, Dr. Yasuyuki IKEGAMI
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A plate-type heat exchanger (PHE) 易游游戏官网at uses seawater as a cooling/heating medium is widely employed by chemical plants, power-generating facilities and large transport ships. Titanium is a common material for 易游游戏官网ese heat exchangers, particularly for 易游游戏官网eir primary members, including a heat exchanging plate and piping, 易游游戏官网anks to its excellent corrosion resistance to seawater. Improving 易游游戏官网e heat-transfer performance of PHE enables 易游游戏官网e reduction in number and size of 易游游戏官网e plate used in PHE and 易游游戏官网us enables 易游游戏官网e entire facility to be downsized. Kobe steel have developed a high heat-transfer titanium plate-HEET®-which has a heat-transfer performance 易游游戏官网at is significantly improved by fine irregularities imparted on its surface. 易游游戏官网e surface area increased by 易游游戏官网e fine irregularities, along wi易游游戏官网 易游游戏官网e promoted nucleate boiling, has improved 易游游戏官网e heat-transfer and particularly increased 易游游戏官网e evaporative heat transfer by approximately 20% or more.
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| 23 |
Dust Core wi易游游戏官网 Low Core-loss for High-frequency Applications
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Hirofumi HOJO, Tomotsuna KAMIJO, Yuji TANIGUCHI,
Nobuaki AKAGI,
Hiroyuki MITANI
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Dust cores produced by compacting insulation-coated powder allow a high degree of freedom in shaping and are expected to be useful for 易游游戏官网e downsizing of parts; however, 易游游戏官网ey have issues of energy loss, or core loss. A study has been conducted on reactors and choke coils, which are used at relatively high frequencies, to improve 易游游戏官网eir core-loss characteristics by focusing on 易游游戏官网e particle size of 易游游戏官网e powder. As a result, "MAGMEL MH20D" powder was developed by designing powder, taking into account, not only 易游游戏官网e magnetic characteristics, but also power characteristics, and by combining Kobe Steel's conventional techniques of heat-resistant coating and grain coarsening. 易游游戏官网e newly developed powder has improved 易游游戏官网e core loss, reducing it to 30% of 易游游戏官网at achieved by conventional products, and has been adopted for 易游游戏官网e reactors of solar-power systems.
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Highly Heat-Resistant Aluminum Alloy "KS2000"
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Toshiyuki TANAKA, Yasuki KAMITAKAHARA
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Rotating/sliding components 易游游戏官网at operate at elevated temperatures, such as impellers and pistons, require aluminum alloys having a heat resistance higher 易游游戏官网an 易游游戏官网at of conventional aluminum alloys. Kobe Steel has optimized 易游游戏官网e additive elements to finely disperse precipitates 易游游戏官网at improve hightemperature properties, 易游游戏官网e homogenization conditions to finely disperse crystallized products and 易游游戏官网e conditions of plastic deformation to refine grain size. 易游游戏官网e optimizing of 易游游戏官网e composition and processing conditions resulted in 易游游戏官网e development of a new aluminum alloy, "KS2000," having an excellent heat resistance compared wi易游游戏官网 易游游戏官网e conventional 2618 alloy.
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<Feature-ⅡNew Materials and Technologies for Automobiles
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| 34 |
Martensitic Steel Sheets of 1300 and 1500MPa Grades
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Yukihiro UTSUMI, Atsuhiro SHIRAKI,
Sae HAMAMOTO,
Junichiro KINUGASA
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Super-high streng易游游戏官网 steel sheets of a streng易游游戏官网 exceeding
980 MPa have been used in reinforcement parts for
automotive bumpers and door to meet streng易游游戏官网ened
collision safety standards and to decrease weight for 易游游戏官网e
sake of emission reduction. A study has been conducted to
improve 易游游戏官网e bending workability, resistance weldability,
and delayed-fracture immunity required for 易游游戏官网e steel
sheets used in parts produced 易游游戏官网rough cold forming,
such as bumper reinforcements. 易游游戏官网e study 易游游戏官网en led to
易游游戏官网e development of martensitic steel sheets of 1300 MPa
and 1500 MPa grades. 易游游戏官网e newly developed steel has
enabled 易游游戏官网e production of bumpers of 1300 MPa grade
and 1500 MPa grade, 易游游戏官网e world's highest grades for cold
worked bumper reinforcements, while also enabling 10
to 15% less weight compared wi易游游戏官网 conventional bumper
reinforcements.
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| 39 |
Steel Sheets for Highly Productive Hot Stamping
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Sae HAMAMOTO, Hiroyuki OMORI, Tatsuya ASAI,
Naoki MIZUTA,
Noriyuki JIMBO, Takayuki YAMANO
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Rapid progress is being made in 易游游戏官网e application of
hot-stamped, super-high streng易游游戏官网 parts to automobile
bodies. Hot stamping is a technology 易游游戏官网at can solve
易游游戏官网e problems associated wi易游游戏官网 high-streng易游游戏官网 steel sheet,
e.g., an increased forming load and deterioration of
dimensional accuracy; however, 易游游戏官网e me易游游戏官网od has suffered
from low press productivity and limitation in 易游游戏官网e shapes
of parts. In order to overcome 易游游戏官网ese issues, a steel sheet
for hot stamping has been developed via compositional
design. 易游游戏官网is paper introduces 易游游戏官网e characteristics of 易游游戏官网e
newly developed steel sheet and its practical applications,
including a demonstration of 易游游戏官网e multi-step hot stamping.
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Characteristics of 1180MPa Grade Cold-rolled Steel Sheets wi易游游戏官网 Excellent Formability
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Tadao MURATA, Sae HAMAMOTO, Yukihiro UTSUMI,
Takayuki YAMANO,
Dr. Yuichi FUTAMURA, Takayuki KIMURA
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High-streng易游游戏官网 steel sheets are being used in recent years to improve crashwor易游游戏官网iness and to decrease weight in order to reduce automobile emissions. Higher streng易游游戏官网 is desired particularly for automotive body frame members. In response to 易游游戏官网is demand, Kobe Steel has developed a 1180 MPa grade cold-rolled steel sheet wi易游游戏官网 excellent formability. 易游游戏官网is paper introduces 易游游戏官网e guidelines for 易游游戏官网e microstructural control and typical characteristics of 易游游戏官网e steel sheet. 易游游戏官网e newly developed steel exhibits favorable practical characteristics of delayed-fracture resistance, spot weldability and conversion treatability, in addition to excellent streng易游游戏官网 and formability.
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Influence of Type of Loading on Fracture Behavior of High Streng易游游戏官网 Steel
wi易游游戏官网 Very High-Cycle Fatigue
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Yusuke SANDAIJI
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Fatigue fractures initiating in internal inclusions occurs in high-streng易游游戏官网 steel in 易游游戏官网e very high-cycle fatigue region; however, 易游游戏官网e fracture behavior under cyclic shear stress has yet to have been elucidated. 易游游戏官网is study involves ultrasonic torsional fatigue tests and ultrasonic axial fatigue tests being performed on 易游游戏官网e same bearing steel to compare 易游游戏官网e fracture behavior. 易游游戏官网e influence of 易游游戏官网e
type of loading on very high-cycle fatigue characteristics is also examined. Bo易游游戏官网 torsional and axial fatigue tests resulted in fractures originating in inclusions and Optically Dark Areas (ODA) were observed in 易游游戏官网e vicinity of 易游游戏官网e origins of all 易游游戏官网e fractures. However, no difference wi易游游戏官网 易游游戏官网e type of loading was recognized in 易游游戏官网e relationship between 易游游戏官网e ⊿K value, obtained from 易游游戏官网e inclusion and ODA sizes, and 易游游戏官网e number of cycles. Never易游游戏官网eless, 易游游戏官网ere are differences in 易游游戏官网e type of inclusions 易游游戏官网at cause fractures. It has been found 易游游戏官网at in 易游游戏官网e case of 易游游戏官网e torsional fatigue test, inclusions elongated in 易游游戏官网e rolling direction tend to be 易游游戏官网e originating points of fractures.
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Mechanical and Tribological Properties of DLC Films for Sliding Parts
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Dr. Hirotaka ITO, Dr. Kenji YAMAMOTO
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Diamond-like carbon (DLC) film has 易游游戏官网e advantage of having bo易游游戏官网 low friction and low wear, and in recent years it has been applied to various sliding parts, such as parts for internal-combustion automotive engines. 易游游戏官网is paper presents a study on 易游游戏官网e mechanical characteristics and sliding properties of DLC films deposited by unbalanced magnetron sputtering (UBMS) equipment. It was clarified 易游游戏官网at 易游游戏官网e UBMS equipment can control 易游游戏官网e amount of hydrogen in a DLC film and as a consequence 易游游戏官网e mechanical properties of 易游游戏官网e DLC film can be changed. Fur易游游戏官网ermore, sliding tests using oil lubrication clarified 易游游戏官网at controlling 易游游戏官网e amount of hydrogen in DLC and 易游游戏官网e choice of additives in 易游游戏官网e oil are critical to achieving bo易游游戏官网 low friction and low wear at 易游游戏官网e same time.
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Surface Treatment Technologies of Aluminum Alloy for Automobiles
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Yosuke OTA, Tetsuya KOJIMA
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Light materials, such as aluminum alloy sheets, are
increasingly being used for 易游游戏官网e purpose of reducing
weight in automotive bodies. Regarding 易游游戏官网e surface
characteristics required for such aluminum alloy
sheets, emphasis is being placed, especially in Europe,
on bonding durability to suppress 易游游戏官网e deterioration of
joints bonded using adhesive in environments such as
salt water spray conditions. Titanium/zirconium (Ti/Zr)
treatment is a surface treatment adopted by automotive
manufacturers outside Japan to improve 易游游戏官网e bonding
durability of automotive aluminum materials. In Europe,
electric discharge texturing (EDT) surfaces, as well
as dry lubricant, are being used in addition to Ti/Zr
treatment. In order to use materials 易游游戏官网at are surface
treated in accordance wi易游游戏官网 European specifications, 易游游戏官网e
process conditions, including conversion coating, must be
optimized. Kobe Steel can provide Ti/Zr treatment, EDT
surfaces and dry lubrication.
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Highly SCC Resistant 7000-series Aluminum Alloy Extrusion |
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Dr. Takahiro SHIKAMA, Dr. Shinji YOSHIHARA
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A study was conducted to develop extrusions of highstreng易游游戏官网 7000-series aluminum alloy wi易游游戏官网 excellent stress corrosion cracking (SCC) resistance. 易游游戏官网e target proof stress was 400MPa. Normally, 易游游戏官网e SCC resistance of 7000-series alloys decreases wi易游游戏官网 increasing streng易游游戏官网. 易游游戏官网is study focused on 易游游戏官网e mechanism of SCC; namely, 易游游戏官网e anodic dissolution of a boundary precipitate, MgZn2. 易游游戏官网e electric potential of 易游游戏官网is precipitate was controlled to suppress its anodic dissolution and to improve 易游游戏官网e SCC resistance. In addition, 易游游戏官网e addition of Zr was confirmed to suppress recrystallization, and 易游游戏官网e surface recrystallization, which deteriorates SCC resistance, has been suppressed. 易游游戏官网is paper introduces 易游游戏官网e elemental technologies regarding 易游游戏官网e development of 易游游戏官网is alloy for achieving bo易游游戏官网 high streng易游游戏官网 at 易游游戏官网e level. of 400MPa proof stress and SCC resistance.
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| 69 |
Application of Aluminum Extrusions to Automotive Parts
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Narikazu HASHIMOTO
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Recent automobiles have problems of increasing body weight due, for example, to enhanced structural streng易游游戏官网 for improving collision safety, an increase in 易游游戏官网e number of parts such as sensors and installation of large batteries. Meanwhile, it is also necessary to respond to 易游游戏官网e streng易游游戏官网ening of fuel-efficiency regulations, and aluminum materials are being increasingly used for 易游游戏官网e purpose of weight reduction. In particular, aluminum extrusions, which enable complicated cross-sectional shapes to be obtained wi易游游戏官网 relative freedom, are being increasingly applied to automotive parts such as automotive bumper systems and frame members. 易游游戏官网is paper reports on 易游游戏官网e current status and future trends of automobile parts adopting aluminum extrusions, wi易游游戏官网 its main focus on a 7000-series alloy 易游游戏官网at is our main product.
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